This project includes studies on medical ecology, and the zoogeography, evolution and systematics of fleas, and is primarily based upon collections made during investigations on vectors and reservoirs of rickettsial and viral infections undertaken in Pakistan, New Guinea, Ethiopia, and other areas. As in the past. data on faunal studies on ectoparasites and their hosts will be used in research on the medical ecology of murine typhus, chigger-borne rickettsiosis, tick typhus and other infections, and on the evolution, geologial history and zoogeography of fleas, their hosts and related infections. Special dissections of parts of fleas will continue to be prepared, and the structures studied from various positions, and not merely the lateral aspect seen in mounted specimens, for this approach has been proven useful in the work on phylogeny, comparative anatomy and adaptations of Siphonaptera. The photomicrographic methods we have developed will be used to illustrate many of the new taxa being described and to depict adaptive structures. During the next year, an intensive study will be undertaken on the distribution, host-relationships and phylogeny of ceratophyllid fleas, and papers will be prepared on the systematics of the Pygiopsyllidae, the major representative of the Order in the Australian Region.